Woven seamless belts for conveyance or power transmission have been used in various segments of the industry. A seamless belt, for instance, is generally manufactured by weaving a cylindrical seamless fabric in the manner of hollow-weave and cutting the fabric in a radial direction.
The diameter of a seamless cylindrical fabric obtainable by such a hollow-weave technique is limited to the breadth of the weaving loom used. Therefore, in order to obtain a cylindrical woven product having a considerably large diameter, such as a seamless belt, it is necessary to sew together a necessary number of unit fabrics into an integral assembly. FIG. 4 is a perspective view showing the conventional large-diameter woven fabric. Indicated at 2a is a unit fabric as a constituent member of a large-diameter cylindrical fabric 2, while the seam formed on sewing such unit fabrics together is indicated at 2b.
Today, long belts for conveyance or power transmission and, therefore, large-diameter cylindrical woven fabrics are finding application in a diversity of fields. The fabrics for such uses are preferably seamless from the standpoint of product performance but as mentioned above it is difficult to manufacture a large-diameter cylindrical seamless fabric by the conventional hollow-weave technique. For example, even when a seamless cylindrical fabric is woven with a loom having an effective machine width of as great as 2.5 m, the hollow-weave technique may provide a fabric having a circumferential dimension of 5 meters at most.
Therefore, in order to obtain a cylindrical fabric having a very large diameter, it is unavoidable, as aforesaid, to sew up a plurality of unit fabrics together. However, the presence of a seam detracts from the homogeneity of the product fabric and, moreover, the practice involves an additional step of machine sewing and means a commensurate addition to labor cost.
The object of the present invention is to provide a novel weaving technology by which a seamless cylindrical woven fabric having an extremely large diameter can be manufactured in one operation even with a loom of the usual effective machine width.